1. Field of the Invention
Generally speaking, the invention relates to apparatus and processes for long term, ambulatory monitoring and accumulation of human physiological data. More specifically, the invention disclosed herein consists of a miniature, solid state recorder for ambulatory monitoring of body signals, electrocardiographic data in particular, and related body motions over extended periods of time in general mobile activities and in particular in athletic activities, sealed against moisture and other contaminants by an encapsulating envelope or inverted pouch, mounted under clothing, and supported by conventional skin mounted electrode adhesive pads attaching the recorder or the encapsulating, sealing envelope directly to the patient""s chest. The recorder and/or sealing envelope can be concomitantly secured by a cord or lanyard around the patient""s neck. The invention discloses novel improvements in data recorder designs specifically related to data collection and analysis of physiological data during sports activity rather than to data collection and analyses of electrocardiographic or other physiological data during clinical patient activity as set forth in co-pending U.S. patent application Ser. No. 09/235,658.
2. Description of the Prior Art
There is an ever increasing need to provide applicable physiological monitoring of cardiovascular performance of individuals undergoing sports activity in major competitive sports such as baseball, football, track, swimming, hockey, water polo, auto racing, and other physical fitness activity in general. There is also a related need for an inconspicuous, hidden monitor that is partially sealed from the immediate environment such that the wearer can perspire heavily and even bathe in a shower without disrupting or disengaging the recording activity. The invention disclosed herein meets the special requirements of a physiological recorder suitable for use in field sports as well as in fitness clubs and country clubs where supervised exercise is offered to individuals of all ages aimed at rehabilitation and weight reduction.
Many and varied long term ambulatory monitoring devices and systems have been developed and marketed over the years with numerous improvements made by applicant herein; most dealing with improved means to provide to the physician, and cardiologist in particular, a higher and higher degree of accuracy in the assessment of a patient""s risk of sudden death from heart arrhythmia and other life threatening signal abnormalities. The monitoring process, as applied to electrocardiography, was named after its inventor and pioneer research physicist, Norman J. Holter, President of the Holter Research Foundation of Helena, Mont. Holter""s co-inventor and technical assistant on the original Holter concept was Wilford R. Glasscock. The original Holter concept and invention was assigned to Del Mar Engineering Laboratories of Los Angeles, Calif., under technology license from the Holter Research Foundation dated Apr. 19, 1962, and was filed in the U.S. Patent and Trademark Office by assignee, Del Mar, on Jul. 6, 1962. The application issued as U.S. Pat. No. 3,215,136 on Nov. 2, 1965 and taught not only a long term, ambulatory ECG recording technique but also Holter""s data reduction and presentation format promoted under Del Mar""s U.S. registered trademarks Electrocardiocorder, AVSEPO, and Arrhythmiagraph. The 136 patent specifically taught a means for processing electrocardiographic signals and more particularly to a means for obtaining large quantities of electrocardiac signals and to a means for facilitating the processing and observing in graphic form of large volumes of such signals in a short interval of time.
Based on the presentations set forth in the foregoing 136 Holter patent, Del Mar Engineering Laboratories produced for clinical cardiology the first complete Holter Monitoring Systems in 1963, which immediately inspired research activity of pioneer. research cardiologists: Dr. Eliot Corday, Dr. Lawrence E. Hinkle, Dr. Herman K. Hellerstein and Dr. John S. Gilson. As a result of several years of clinical testing by these physicians of the Holter Monitoring procedure resulting in numerous publications in medical journals on results emanating from test on hundreds of patients, Holter Monitoring was endorsed and recommended as a new revelation in cardiovascular clinical practice, and was eventually adopted as a standard practice worldwide.
Since 1965, a progression of Holter improvement patents have issued over the years, notably that of Oct. 31, 1978, U.S. Pat. No. 4,123,785, xe2x80x9cRecorder for Cardiac Signals with Manually Activated Event Markerxe2x80x9d by inventors Isaac R. Cherry and Donald L. Anderson of Del Mar Avionics, successor to Del Mar Engineering Labs. The 785 patent disclosed a small, hip/side mounted tape recorder for ambulatory recording of cardiac signals over a twenty-four hour interval and included a clock with visual display and a patient event marker. Cardiac signals were simultaneously recorded on two tracks on magnetic tape wherein the event marker function could also be recorded and activated by the patient to denote the happening of a specific event sensed by the patient that can be easily recognized on play back in relation to heart activity at the time. The 785 Cherry patent was followed by yet many other noteworthy inventions.
The forgoing U.S. patents taught many important developments in Holter Monitoring technology but were yet followed by a series of other prior patents of Del Mar Avionics dealing with Holter Monitoring concepts. U.S. Pat. No. 4,532,934, was issued August 1985, titled xe2x80x9cPacemaker Monitoring Recorder and Malfunction Analyzerxe2x80x9d, by inventor George J. Kelen, M.D. The Kelen 934 patent disclosed a hip/side mounted magnetic tape recorder which detects and records sequential pacemaker spikes in one channel in a waveform compatible with corresponding ECG signals recorded in a second tape channel. The system further includes an analysis module connected to the playback unit for receiving both the ECG and pacer spike signals and is adapted to play back both channels of information at 120 times recording speed. An analysis module in the recorder has counters to accumulate the number of paced beats and fusion beats. The system is further configured to sense malfunctions, failure to sense, failure to capture, and abnormal bradycardia.
U.S. Pat. No. 5,109,862 issued May 8, 1992 and was titled xe2x80x98Method and Apparatus for Spectral Analysis of Electrocardiographic Signals,xe2x80x99 by inventors George J. Kelen, M.D. and Raphael Henkin, Ph.D. The Kelen 862 patent discloses a signal processing and analysis method and apparatus for plotting and measuring ECG signals where the graphic plots and numeric parameters measured reveal abnormalities of electrical conduction within the heart thought to anticipate abnormal heart rhythm, arrhythmia. The invention employs Fourier Analysis of short overlapping segments of ECG signal to create a three-dimensional electrocardiogram map.
U.S. Pat. No. 5,205,295, issued Apr. 27, 1993 xe2x80x9cMethod and Apparatus for Holter Recorder with High Resolution Signal Averaging Capability for Late Potential Analysis,xe2x80x9d by inventors Bruce Del Mar and Isaac R. Cherry. The Del Mar 295 patent discloses a method for digital signal averaging of selected signals and storing for future playback. The averaged signals, several times per hour in a 24-hour period, are correlated with previously defined correlation coefficients to yield summated results that have eliminated non-repetitive noise. Information so accumulated enable micropotential analysis of cardiac electrical activity.
Since 1996 digital data storage capacity in lightweight disc drives and printed circuit card, flash memory components has progressed in production to the point where solid-state ambulatory physiological recorders can be made at reasonable cost. Such recorders offer an advantage over prior art ambulatory physiological tape recorders because digital recorders have no moving parts and no need for separate analog-to-digital data conversion. Solid-state recording now represents a formidable improvement in the art of ambulatory physiological recording.
Long-term ambulatory physiological and Holter recorders have been conventionally worn in a protective pouch slung by straps over the shoulder outside the clothing or hung on a person""s belt, again outside the clothing. Many problems and inconveniences can occur while wearing such conventional ambulatory physiological recorders, especially because of the necessary prolonged, continuous recording times involved. Dressing and sleeping become troublesome due to the long wire harness required on existing recorders. Electrodes often get pulled off the chest by the wire harness during sleep and active physical activities. The recorder may also receive rough treatment from dropping to the floor or exposure to other hostile environments. With the invention disclosed herein, compactness and simplicity replace a variety of components and complication. With the new invention disclosed herein, exercise, including walking and running, is unrestricted. The daily routine of sleeping, dressing and bathing in a shower need not change! And, for the clinician, this invention can create more reliable long-term monitoring of physiological signals. Of special note, the ambulatory data recorder of the invention incorporates design features especially suited to long term wear under wet or dry conditions wherein there may be a broad array of arm and leg motion with or without protective clothing covering the athlete and the monitor.
As will be more particularly described herein, the ambulatory data recorder of this invention utilizes compact, contiguous, and high continuity integrated circuitry; A-to-D converters; a CPU operating system; a physiological sensor elements; acceleration detector element; printed circuit, flash memory and DC power to record at least one, but preferably three, channels of physiological kinetic data, with optional event marking and optional activity monitoring, as well as means to program specific periods of recording with or without data compression. All the foregoing functions and elements are sealed within a compact recorder housing disposed within an envelope or inverted pouch protecting the recorder from water and environmental contaminants. In one embodiment of the invention, the recorder is provided with at least one adhesive skin patch, but preferably four, that hold the monitor on the patient""s chest with the option of a backup security lanyard hung around the patient""s neck in the manner is of a necklace to also support the recorder. In a second embodiment, the recorder housing is disposed within a sealing envelope or inverted pouch, wherein said envelope is attached by at least one, but preferably a pair of swivel type adhesive electrode elements to enable less restricted body movements. The recorder system has multiple sensor attachments and serial and parallel output ports to download recorded data for digital analysis and display of a full disclosure or summary data report on a conventional Personal Computer (PC) or other digital retrieval system.
It is a primary object of the invention to provide an ambulatory physiological data recorder designed to give information on cardiovascular electrophysiology together with a measure of corresponding physical activity on athletes and fitness performers during the practice of their sport.
It is a another general object of the invention to provide for a long term, ambulatory physiological data recorder design to obtain more complete and reliable ambulatory physiological recordings by providing a self contained recorder device mounted on the patient""s skin directly adjacent the organ or system to be monitored, particularly the heart, but not necessarily limited thereto, thereby diminishing the length of the body attached sensors and leads thereto.
It is yet another substantial object of the invention to enable a physician to attach a compact recorder system to a patient in a manner that is out of sight and inconspicuous, as well as more convenient and comfortable to wear.
Another object is to provide for higher electrical continuity of sensor contacts made possible by the simplicity of wearing this novel recorder at the signal source and avoiding recording failures or introduction of artifact attributed to loose rigging of lengthy leads and sensor apparatus on the body;
Another object is to increase recorder continuity and reliability by utilizing a double sealing, adhesive ring around each electrode sensor;
Yet another object of the invention is the provision for recording ambulatory physiological signals in an unseen, covert fashion under the patient""s clothing;
Still another object is to provide an independent ambulatory physiological recording means and process that does not need to change patient""s daily routine, e.g. exercising, bathing, getting dressed, by placing the recorder within a semi sealed envelope or inverted pouch to ward off water from while bathing in a shower or from a heavy perspiration environment;
Another object is to provide ambulatory physiological recording without restriction to daily exercise or position of the body or limbs, including walking and running;
Yet another object is to reduce the cost of obtaining ambulatory physiological recordings for the patient, the medical practitioner, and the government by incorporation of micro miniature, digital solid state electronics;
Still another object of the invention is to provide an ambulatory physiological recording system wherein body activity, acceleration sensors located directly within the recorder can provide information on body orientation, activity and acceleration simultaneously with other sensor data to measure the relationship between physical activity and sensor data throughout the recording period;
Another object is to provide an ambulatory physiological recorder that is pliable and comfortable to wear by having flexibility to fit the contours of the body;
Another object is to utilize a lanyard extending around the athletes neck to lend additional support of the monitor suspended over the body organ, e.g. the heart, to be monitored; and
Yet another object is to provide a readily available ambulatory physiological recorder for short-term recording of body signals while undergoing an informal treadmill or improvised stress test using a limited number of sensors. The period of recording may be short, but the data analysis can be reported quickly from the digital write out device, already available for other related purposes. Such a stress test can be conducted in the physician""s office as an adjunct to other long-term physiological monitoring tests.